Log scaler



March 8, 1938., Q CLARKE ZJHQ'YE)? LOG'SCALER Filed May 18, 1934 Invent. DI

In E- CLARKE Abtur'nE s Patented Mar. 8, 1938 UNITED STATES PATENT OFFICE Canad Application May 18, 1934, Serial No. 726,233

1 Claim.

My invention relates to improvements in log scalers, and the object of the invention is to devise an instrument which can be used for measuring the cross-sectional diameter of the log and which will then automatically compute the crosssectional area of the log through the medium of logarithmic means incorporated therein. Thus to obtain the number of cubic feet in the log it will only be necessary for the user to take the reading on the instrument and multiply it by the length of the log.

If so desired the computing device can be so arranged as to give automatically the number of cubic feet in a log of a predetermined length.

A further object is to construct a device incorporating the above characteristics which will be accurate in use, simple in construction and sufficiently sturdy to withstand rough usage.

A still further object is to provide additional means for indicating the number of logs scaled by the device.

With the above and other objects in view which will hereinafter appear as the description proceeds, my invention consists, in its preferred embodiment, of the construction and arrangement hereinafter described and illustrated in the accompanying drawing in which:

Fig. 1 represents a longitudinal section through the device constructed according to my invention.

Fig. 2 is a longitudinal section taken at right angles to Fig. 1.

Fig. 3 is a fragmentary elevational view of the head of the device.

Fig. 4 is an inverted plan view, and

Fig. 5 is a horizontal section taken through the line 55 (Fig. 1).

Like characters of reference indicate corresponding parts in the different views.

The casing I of the device, preferably of cylindrical form and with an offset head 2, is provided in its reduced lower end 3 with a transverse spindle 4 journalled therein and having one end protruding from the casing. Such exterior end of the spindle t carries the serrated wheel 5 which is adapted to be drawn or rolled over the diameter of the log end.

A longitudinal cylindrical member 6 is journalled in the barrel of the device by being mounted in the upper and lower bearings l, preferably of an anti-friction type, said member 6 being, of course, disposed concentrically with the barrel. A groove 8 of generally helical form is cut in the outside face of the member 6, said groove representing the logarithmic curve necessary for causing the indicating device 9 to indicate the cross-sectional area of the log corresponding to the circumferential distance travelled by the wheel 5 in being drawn across the diameter of the log end as will hereinafter be more fully described.

The spindle 4 also carries a pinion 1!! which meshes with a gear ll secured on a second cross spindle i2 journalled in the lower end 3 of the casing i, and this second spindle l2 also carries a bevel gear I 3 meshing with a bevel pinion 54 provided on the lower end of a vertical shaft !5 disposed axially of the member 6 and easing or barrel l and extending freely through the lower end of the former but being keyed or otherwise secured to the upper end thereof. The shaft i5 may be suitably journalled at its lower end, for instance, in the bearing I6. A spiral spring 51 surrounds the shaft it, being anchored at its upper end to the shaft and its lower end being connected to any stationary part of the device, for instance, the stud I8 (Fig. 1) upon which a sprocket wheel 59 is journalled.

The sprocket wheel i9 is connected by a chain 2! with a sprocket wheel 2| journalled in the head 2 of the device and such latter sprocket wheel 25 carries a part 22 of a ratchet type clutch adapted to engage its complementary part 23 secured to the spindle 24 of the indicating device 9, which latter may be of the general type of odometer or cyclometer indicators and is, therefore, not described in detail as it forms no part of the present invention.

A dog 25 is secured on one portion of the chain 20 as shown in Fig. 2 and such dog is provided with a projection 26 adapted to travel in the logarithmic groove 8 as the latter is rotated. At the return limit of its travel the dog 25 trips the lever 21 of a trip indicator 28 of any well known type, which latter is disposed in the offset portion of the head 2 as is the indicator 9.

The device is actuated as follows:-

The instrument is held in the hand of the user and the wheel 5 is drawn across the diameter of the log end. As the wheel is thus rotated, through the intermediary of the gearing in the lower end 3 of the casing l the shaft 15 is rotated, consequently rotating its connected member 6 and causing the dog 25 to descend. As the dog is secured on the chain 29, the latter is driven and with it the connected sprocket wheel 2| which, through the medium of the ratchet clutch 22, 23, causes the rotation of the elements of the indicator 9. Through the intermediary of the logarithmic device the indicator 9 is so arranged as to give its reading in terms of the cross-sectional area of the log. When the serrated wheel 5 is run along the diameter of a log end, the number of revolutions of the spindle 4 caused thereby will be equal to the number of times the circumference of the wheel 5 is contained in the log diameter, and for each revolution of the spindle 4 the shaft l5 and the cylinder 6 carried thereby will rotate an amount which is governed by the ratios between the gears HI and I I and I3 and I4 through which rotation of the wheel 5 is converted into rotation of the cylinder 6. Thus when the wheel 5 is run along the diameter of a log end, the cylinder 6 will be rotated an amount proportional to the diameter of the log end. The groove 8 is of such form that the linear distance moved by the projection 26 is proportional to the logarithm of the number of revolutions made by the cylinder 6 to cause such movement, so that the distance travelled by the projection 26 is a function of the logarithm of the diameter of the log end. Since the area of a circle is proportional to the square of the diameter and thus to the logarithm of the diameter, if the circumference of the wheel 5, the gear ratios in the train I, H, l3 and M, the diameter of the cylinder 6 and the form of the groove 8 are properly chosen, the units of area of the log end traversed by the wheel 5 will be indicated by the indicator 9. Logs scaled are usually of predetermined length, say 8, 10 or 12 feet or even longer and if the instrument is to be designed to function on a log of any predetermined length the reading on the indicator 9 may be the cubic feet in the log. This would be achieved by merely altering the figures on the indicator to suit, but this would require a separate instrument for each different length of log.

When the wheel 5 is lifted from the log end after traversing its diameter, the spring I! which has been wound up during the measuring operation will unwind rotating the member 6 in the reverse direction and thus cause the dog to ascend to its initial position. When it reaches each upper return limit of its travel it trips the lever 21 of the trip indicator. Such trip indicator functions after each measuring operation and will thus indicate the number of logs scaled.

During the return of the dog 25 and chain 20 to their initial position after measuring a log, owing to the provision of the ratchet clutch 22, 23, the indicator 9 will be inoperative.

As many modifications may be made in the invention without department from the spirit of the same or the scope of the claim the form shown is to be taken in an illustrative and not in a limiting sense.

What I claim as my invention is:

A portable log scale comprising a cylindrical casing constituting a hand grip for the instrument, a rotatable member journalled exteriorly at the lower end of the casing substantially on the prolongation of its longitudinal axis, a rotatable cylindrical member having a logarithmic groove in its outer surface journalled in the casing with its axis of rotation coincident with the longitudinal axis thereof, gear means between the rotatable member and the rotatable cylindrical member for rotating the latter if the former is rotated, an indicator on the upper end of the casing, and means between the indicator and the logarithmic groove of the rotatable cylindrical member for causing the indicator to give a reading commensurate with the rotation of the rotatable cylindrical member.

JOSEPH CHARLES CLARKE. 

